Dew and humidity monitoring is essential to prevent potentially catastrophic consequences in advanced industries such as oil and gas, petrochemical, semiconductor manufacturing, food and beverages, pharmaceuticals, lithium battery manufacturing, and gas-insulated high-voltage equipment. Furthermore, dew monitoring is required in various drying and heat treatment processes such as plastic molding and metal treatment, as well as in compressed air pipelines to prevent ice formation, equipment corrosion, and poor end-product quality.
There are currently a number of dew and humidity sensors on the market. The most common variety is sensors with electrical probes, which operate by measuring the change in certain electrical parameters, such as capacitance or resistance. Alternatively, there exist optical dew and humidity sensors, which function by measuring the reflection or refraction of light by either a chilled mirror or an optical waveguide through a free-space optical set up. Further, studies have been conducted regarding the use of fiber optic sensors to measure humidity and moisture. Such sensors operate by methods such as direct spectroscopy, evanescent waves, in-fiber grating, interferometry, or a combination of these methods.
The dew and humidity sensors currently available have several drawbacks. These sensors are not suitable for operation in hazardous or combustible locations, are not immune to electromagnetic interference, and are not small enough to be used in remote or difficult to access locations. Therefore, there exists a need for a dew and humidity sensor that meets these criteria as well as being of low cost, easy to operate, easy to maintain, and providing for remote, parallel and distributive operation.